Picture encoding device and picture encoding method

A picture encoding method that encodes a picture and encodes a difference quantization parameter in a unit of a quantization coding block which is divided from the picture and is a management unit of a quantization parameter, comprising:

• a quantization parameter derivation step of deriving a quantization parameter of a first quantization coding block;
• a prediction quantization parameter derivation step of deriving a prediction quantization parameter using the quantization parameters of two quantization coding blocks which precede the first quantization coding block in order of encoding;
• a difference quantization parameter derivation step of deriving a difference quantization parameter of the first quantization coding block, using a difference between the quantization parameter of the first quantization coding block and the prediction quantization parameter;
• and
• an encoding step of encoding the difference quantization parameter,
• wherein the prediction quantization parameter derivation step derives the prediction quantization parameter using two quantization parameters:
• one quantization parameter of a previous quantization coding block which immediately precedes the first quantization coding block to be encoded in order of encoding and another quantization parameter of a quantization coding block which precedes the previous quantization coding block in order of encoding and is not spatially neighboring the first quantization coding block to be encoded.